Extandable exterior rearview mirror assembly

ABSTRACT

An extendable exterior rearview mirror assembly includes a mirror subassembly, a bracket which is adapted for mounting to a vehicle, and a support which mounts the mirror subassembly to the bracket. Support extends into the housing which is movable along the support. The housing includes a retracted position and at lease one outboard position, which define a direction of extension. The mirror assembly further includes a drive assembly which is supported in the housing and drivingly coupled to the support. The drive assembly selectively moves the housing along the support. The mirror assembly further includes a clutch mechanism which drivingly decouples the drive assembly from the support when a force of sufficient magnitude is applied to the housing in the direction of extension such that the housing can be manually moved along the support.

This application is a divisional application of application Ser. No.09/267,532, filed Mar. 12, 1999, and now U.S. Pat. No. 6,325,518, PeterJ. Whitehead and Michiel P. van de Ven, entitled EXTENDABLE EXTERIORREARVIEW MIRROR ASSEMBLY, the disclosure of which is hereby incorporatedby reference herein.

TECHNICAL FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to an extendable exterior rearview mirrorassembly for mounting on a vehicle and, more particularly, to anexterior rearview mirror for mounting on a vehicle which can beselectively extended by the occupant of the vehicle to increase thefield of view for example when the vehicle is used for towing a trailer,camper, another vehicle, or the like.

Conventional towing mirrors include a reflective element housed in aframe that is mounted to the body of a vehicle by a support and mountingbracket. The support extends the mirror a greater distance from the bodyof the vehicle than conventional exterior rearview mirrors in order toprovide an unobstructed view to the rear of the towed object. Forexample, in U.S. Pat. No. 3,119,591 to A. J. Malecki an extendablerearview mirror assembly is disclosed which includes a rigid support foreccentrically mounting the mirror assembly in a fixed extended positionfrom the vehicle. However, these fixed extended rearview mirrorassemblies increase the width of the vehicle X in some vehicles, thewidth is increased beyond the maximum width allowed by conventionalvehicle transport trucks which deliver the vehicles to the dealership.Therefore, these extended mirror assemblies are typically installed atthe dealership which ultimately increases the cost of the vehicle.

In addition, the fixed extended rearview mirror assemblies is of limiteduse for a driver who only occasionally tows a trailer. Since such mirrorassemblies substantially increase the width of the vehicle, they hampernormal maneuvering through passages such as those defined by garage dooropenings, drive-through banking structures, and the like. Furthermore,they are more vulnerable to being damaged or to causing damage thanconventional exterior rearview mirrors, especially when used by aninexperienced driver. This inconvenience is compounded by the fact thatnot only do these extended rearview mirrors generally detract from theappearance of the vehicle, they increase the cost of the vehicle.

In response to the needs of drivers who only occasionally tow objects,several extendable mirror assemblies have been developed. For example,in U.S. Pat. Nos. 5,513,048 and 5,489,080 extendable mirrors aredisclosed which includes telescoping tubular members which are fixed inposition by threaded fasteners. Though simple in construction, thesetelescoping members typically require the operator to use a tool toadjust the position of the mirror. Moreover, they tend to increase thevibration of the mirror assembly, which may in turn loosen theconnection between the telescoping members of the mirror assemblyespecially when the mirror assembly is in the outboard position.

In U.S. Pat. No. 5,546,239 to Lewis, an extendable mirror element isdisclosed in which the mirror element is extended from the mirror casingto an outboard position. Again the mounting bracketry lacks thestructure to perform well in vibration. Consequently, the mirror elementis more vulnerable to damage.

More recently, manually extendable rearview mirror assemblies haveincluded one or more mounting arms which releasably engage the housingof the mirror subassembly to permit manual extension of the mirrorsubassembly along the mounting arms, such as disclosed in pending U.S.patent application Ser. No. 08/838,877, filed Apr. 19, 1997, by Peter J.Whitehead, now U.S. Pat. No. 5,969,890, which is assigned to DonnellyCorporation of Holland, Mich., which is herein incorporated by referencein its entirety. Other more recent extendable mirrors include one ormore mounting arms which frictionally engage the mirror subassemblyhousing to permit selective manual adjustment of the position of thehousing along the mounting arm, such as disclosed in pending U.S. patentapplication Ser. No. 08/821,458 filed Mar. 21, 1997, to Steven G. Hoek,now U.S. Pat. No. 5,903,402, which is assigned to Donnelly Corporationof Holland, Mich. and which is herein incorporated by reference in itsentirety.

In contrast, U.S. Pat. No. 5,572,376 to Pace discloses an electricallyactuated extendable vehicle mirror which includes a rack and pinionsystem and a drive motor to translate the mirror longitudinally alongthe mirror support arm. Despite the enhanced control of the position ofthe mirror, the Pace assembly does not include any safety features thatprevent the mirror from being damaged when it inadvertently overextendedor provide a manual override option which are both highly desirable. Inaddition, the Pace drive assembly is relatively complicated and theassociated parts increase the weight of the mirror assemblysignificantly. With an increased number of parts, the cost ofmanufacture increases. Further, weight increases of this magnitude tendto increase the vibration of the mirror assembly and degrade theperformance of the mirror.

Consequently, there is a need for an extendable exterior rearview mirrorthat can be installed at the factory, which provides extended field ofview required when towing vehicles and yet be retracted to a normaloperating position where it does not hamper the maneuverability of thevehicle. Moreover, the extendable rearview mirror should have minimalimpact on the vibration of the mirror assembly and be relatively easy toadjust between non-towing and towing positions by the occupant of thevehicle without the need for tools and yet provides a safety mechanismand manual override option.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an improved extendableexterior rearview mirror assembly, especially suited for towingvehicles, which is selectively adjustable between a retracted positionfor normal non-towing use and one or more extended positions in whichthe mirror assembly is outboard of its normal position allowing anincreased field of view to the rear of a towed trailer or the like.These functions are provided by a drive assembly which allows theoccupant of the vehicle to selectively adjust the position of the mirrorhousing and a clutch mechanism which provides a safety release for thedrive assembly and, further, allows manual adjustment of the mirrorhousing.

According to one aspect of the invention, an extendable exteriorrearview mirror assembly includes a mounting bracket adapted formounting to a vehicle, a support supported by the mounting bracket, amirror subassembly having a housing and a reflective element supportedby the housing and being movably mounted on the support, and a driveassembly supported in the housing. The drive assembly selectivelyengages the support to move the housing with respect to the support toadjust the position of the mirror subassembly. The extendable exteriorrearview mirror further includes a clutch for decoupling the driver fromengagement with the support which provides a safety mechanism and amanual override option. In one form, the mirror subassembly isselectively moved along the support between inboard and outboardpositions by the drive assembly.

In another form, the support comprises a pair of support arms, with thesupport arms extending into the housing of the mirror subassembly. Thesupport arms are interconnected by a member with the member beingcoupled to the drive assembly. In one form, the member is releasablycoupled to the drive assembly.

According to another form, the drive assembly includes a motor, a drivepulley, an idler pulley, and a belt which extends around the drivepulley and the idler pulley. The belt is coupled to the support suchthat when the motor drives the drive pulley, the housing moves along thesupport. The support may comprise a pair of arms, with the support armsbeing interconnected by a member and with the member being coupled tothe belt.

In yet another form, the drive assembly includes a motor and a pluralityof rollers. The motor drives the rollers to frictionally engage thesupport to move the housing along the support. For example, the drivermay include a drive rod, with the rollers being mounted on the drive rodwith both the drive rod and the rollers extending into the support. Thesupport may comprise a tubular member, with the rollers engaging theinner surface of the tubular member to thereby move the housing alongthe support.

According to yet another form of the invention, the drive assemblyincludes a lead screw and a motor. The lead screw extends through aportion of the support and is driven by the motor to move the housing onthe support. Preferably the support includes a pair of support arms,with the support arms being interconnected by a member. The lead screwextends through the member. Optionally, the member includes flexiblethread engaging portions for engaging the lead screw whereby theflexible thread engaging portions disengage from the lead screw when aforce is applied to the housing in the direction of the extension thuspermitting manual adjustment of the housing along the support.

In another form, the support includes a tooth rack. The drive assemblyincludes a motor and at least one movable piston which is driven by themotor to drivingly engage the tooth rack to selectively move the housingalong the support. In one form, the piston is mounted on a shaft, whichis driven by the motor. The shaft imparts motion to the piston and movesthe piston in a cycloidal path to drivingly engage the tooth rack.Optionally, the drive assembly may include a plurality of piston membersand a corresponding plurality of drivers, with the drivers selectivelyand sequentially moving the pistons into engagement with the tooth rackto move the housing along the support. For example, the drivers maycomprise solenoids.

According to another aspect of the invention, an extendable exteriorrearview mirror assembly includes a mirror subassembly having a housingand a reflective element, a bracket which is adapted for mounting to avehicle, a support which is mounted to the bracket, and a link whichpivotally mounts the mirror subassembly to a the support. The mirrorassembly further includes a drive assembly supporting the housing whichis drivingly coupled to the support and moves the housing between aretracted position and at least one extended position which define adirection of extension. The drive assembly includes a clutch fordecoupling the drive assembly from the support when a force is appliedto the housing in the direction of extension to provide manualadjustment of the position of the housing.

As will be understood, the extendable exterior rearview mirror assemblyof the present invention provides numerous advantages over the priorknown mirror assemblies. The extendable exterior rearview mirrorassembly provides an extended field of view for towing vehicles and yetcan be retracted to a normal operating position by the occupant of thevehicle to return the vehicle to its normal width. Therefore, theextendable exterior rearview mirror assembly of the present inventioncan be installed at the factory. Moreover, the extendable mirrorsubassembly of the exterior rearview mirror assembly includes a safetyrelease so that the mirror subassembly can be manually adjusted and,further, the drive assembly is protected from damage if the mirrorassembly is inadvertently overextended.

These and other objects, advantages, purposes and features of theinvention will become more apparent from the study of the followingdescription taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of an extendable exterior rearview mirrorassembly of the present invention installed on a vehicle;

FIG. 2 is a partial fragmentary view of the extendable exterior rearviewmirror assembly of FIG. 1;

FIG. 3 is an enlarged view of a clutch assembly of the exterior rearviewmirror assembly of FIG. 2;

FIG. 4 is a side elevation view taken along lines IV—IV of FIG. 2;

FIG. 5 is a partial fragmentary view of the extendable exterior rearviewmirror assembly of FIG. 1 illustrating a second embodiment of the driveassembly;

FIG. 5A is an enlarged view taken along line VA—VA of FIG. 5 of a clutchmechanism of the rearview mirror assembly of FIG. 2;

FIG. 5B is a similar view to FIG. 5A of a second embodiment of a clutchassembly of the present invention;

FIG. 6 is a partial fragmentary view of a third embodiment of anextendable exterior rearview mirror assembly of the present invention;

FIG. 7 is an enlarged view of the clutch mechanism of FIG. 6;

FIG. 7A is a cross-sectional view taken along line VIIA—VIIA of FIG. 7;

FIG. 8 is a partial fragmentary view of a fourth embodiment of theextendable rearview mirror assembly of the present invention;

FIG. 9 is an enlarged view of a section of the drive assembly of FIG. 8;

FIG. 9A is a cross-section view taken along line IXA—IXA of FIG. 9;

FIG. 10 is a partial fragmentary view of a fifth embodiment of anextendable exterior rearview mirror assembly of the present invention;

FIGS. 11A through 11C are enlarged views of the drive assembly of FIG.10 illustrating a sequence for actuating the drive pistons of the driveassembly;

FIG. 12 is a partial fragmentary view of extendable rearview mirrorassembly of FIG. 10 with another embodiment of the drive assembly of thepresent invention;

FIGS. 13A through 13D are enlarged views of the driver piston of thedrive assembly of FIG. 12 illustrating the motion of the driver piston;

FIG. 14 is a partial fragmentary view of a seventh embodiment of theextendable rearview mirror assembly of the present invention;

FIG. 14A is a cross-section view taken along line XIVA—XIVA of FIG. 14;

FIG. 15 is a plan view of an eighth embodiment of the extendableexterior rearview mirror assembly of the present invention;

FIG. 15A is a cross-section view taken along line XVA—XVA of FIG. 15;and

FIG. 16 a partial fragmentary view of a ninth embodiment of theextendable exterior rearview mirror assembly of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, an extendable exterior rearview mirror assembly 10of the present invention is shown mounted to a vehicle 12. Rearviewmirror assembly 10 includes a mounting bracket 14, a housing support 16mounted to bracket 14, and a mirror subassembly 18. Mounting bracket 14is preferably mounted to vehicle 12 by conventional methods, such as byfastening with a pair of threaded studs which pass through the vehicleand are secured thereto with nuts. Support 16 may comprise a fixedsupport, a break-away support, or a folding support. In the illustratedembodiment, support 16 comprises a break-away support.

As best seen in FIG. 2, mirror subassembly 18 includes a mirror case orhousing 20 and reflective element assembly 22, which is supported inmirror housing 20. Reflective element assembly 22 includes a reflectivemirror element 24 and a backing plate 26, which supports reflectivemirror element 24 in housing 20. Reflective mirror element 24 maycomprise a conventional nonelectro optic planar or convex mirror elementincluding a metallic reflector coated glass substrate, such as with athin chromium or chromium alloy reflector coating, or a non-metallicreflector layer, such as a dichroic layer as described in U.S. Pat. No.5,207,492 to Robert et al. or a reflector comprising a siliconreflective layer such as described in U.S. Pat. No. 5,535,056 to Caskeyet al., which are herein incorporated by reference in their entireties.Alternatively, reflective element 24 may comprise a variable reflectiveelectro optic element, such as electrochromic mirror element comprisingone of several types of electrochromic elements, for example an elementof the electrochemichromic type, which is disclosed in U.S. Pat. No.5,140,455 issued to Varaprasad et al., or may be of the solid state typesuch as disclosed in U.S. Pat. No. 4,712,879 issued to Niall R. Lynam etal., U.S. patent application Ser. No. 08/023,675, filed Feb. 22, 1993,by Varaprasad et al., U.S. patent application Ser. No. 08/913,557, filedFeb. 8, 1994, by Varaprasad et al., and U.S. patent application Ser. No.08/238,521, filed Mar. 5, 1994, by Varaprasad et al., now U.S. Pat. No.5,668,663, all commonly assigned with the present application toDonnelly Corporation of Holland, Mich., the disclosures of which areherein incorporated by reference in their entireties. Suchelectrochromic elements comprise an electrically responsiveelectrochromic medium that modulates reflectivity from a reflectiveelement. Such electrochromic mirror elements are continuously variableand exhibit multiple reflectant states as the voltage applied thereto isvaried. Alternately, reflective element 16 may comprise other electrooptic mirror elements such as a liquid crystal mirror and the like.Where reflective element 16 comprises an electrochromic mirror element,the electrochromic mirror element is preferably driven by signalsproduced by a variable reflectant system of the type disclosed in U.S.patent application Ser. No. 08/316,047, for a “Modular VariableReflectant Mirror Assembly”, filed Sep. 30, 1994, by Kenneth L.Shierbeek et al., now U.S. Pat. No. 5,569,423, which is hereinincorporated by reference in its entirety. In addition, mirrorsubassembly 18 may include a manual or electric actuator to move thereflective element, rain sensors, blind spot detection systems, compasssystems, intrusion detection systems, vehicle security lights, turnsignal indicators, keyless entry systems, and trainable garage dooropener systems, and the like. For details of several other vehiclesystems which can be incorporated into subassembly 18, reference is madeherein to pending United States patent application entitled “ModularRearview Mirror Assembly Including an Electronic Control Module”, Ser.No. 08/702,228, which was filed on Aug. 23, 1996, by Niall Lynam et al.,now U.S. Pat. No. 6,019,475, and which is assigned to DonnellyCorporation of Holland, Mich., the disclosure of which is incorporatedby reference herein in its entirety.

Housing 20 is preferably a modular housing and injection molded fromnon-electrically conductive material, such as suitable thermoplasticresin. Housing 20 includes a rearward facing opening 28, in whichreflective element assembly 22 is positioned, and one or more sleeves 30for receiving housing support 16. In the illustrated embodiment, housingsupport 16 includes a pair of support arms 32 and 34, which extend intorespective sleeves 30 of housing 20 for supporting housing 20 thereon.Support arms 32 and 34 may comprise tubular members and are, preferably,injection molded from non-electrically conductive material, similar tohousing 20. Housing 20 moves in and out on support arms 32 and 34 topermit the extension of mirror subassembly 18 from vehicle 12 between anin board position and one or more outboard positions. The outboardpositions provide larger fields of view which is suitable for viewingrearward towed objects, such as campers, trailers, or the like. Theposition of housing 20 is selectively controlled by a drive assembly 36,as will be discussed in more detail below.

As best seen in FIG. 2, support arms 32 and 34 are optionally pivotallymounted to mounting bracket 14 on a pivot bushing 40 and are adapted forlimited pivotal movement about bushing 40 between a normal operatingposition and a break-away position, such break-away mountings are wellknown in the vehicle mirror assembly art.

As noted above, support arms 32 and 34 extend into housing 20 throughsleeves 30 and, further, are interconnected at their free ends 32 a and34 a by a plate member 42. Drive assembly 36 includes a motor 44 and adrive or lead screw 46, which includes a reduction gear 48 that isdriven by a drive gear 50 of motor 44 (FIG. 4). Motor 44 is preferablypowered by the vehicle battery and is electrically coupled to thevehicle electrical system through electrical leads 44 c, which may bebundled along with other wiring in a harness, preferably an extendableharness, such as a spring mounted or coiled harness. It should beunderstood, further, that electrical leads 44 c may be electricallycoupled to an electronic module or the like housed in mirror subassembly18, support 16, or bracket 14. Further, motor 44 is preferably actuatedby a remote switch or toggle which is mounted in the vehicle cabin and,more preferably, in the vehicle cabin in close proximity to the driver.In addition, the switch or toggle preferably includes selection betweenthe left and right mirror assemblies so that each mirror assembly can beindividually controlled to extend or contract. Drive screw 46 extendsthrough housing 20 and is optionally supported on opposed side walls 52and 54 for example by bushings 56 and 58. Motor 44 is supported by motorsupports 44 a and 44 b, which are in turn supported by housing wall 20a. Optionally, motor supports 44 a and 44 b may be formed as an integralpart of housing 20 during molding. In a similar manner, bushings 56 and58 may be directly adhered to housing wall 20 a or optionally may bemounted in bushing supports which are either adhered to or molded alongwith housing 20. Drive screw 46 extends through plate member 42 toselectively couple drive assembly 36 to support 16. Plate member 42includes flexible tongues or fingers 60 with tapered distal ends 62which form threads for engaging threads 64 of drive screw 46. In thismanner, when motor 44 drives drive screw 46, housing 20 is translatedalong support arms 32 and 34. Furthermore, flexible fingers 60 aresufficiently flexible to permit disengagement of tapered portion 62 fromthreads 64 of drive screw 46 when a force is applied to housing 20 inthe direction of extension. In this manner, flexible fingers 60 form aclutch and permit manual override of drive assembly 36. In addition,flexible fingers 60 provide a safety override, for example when housing20 is driven to extend into a rigid or fixed object, tapered portion 62will disengage from threads 64 to drivingly decouple drive assembly 36from support 16.

It should be noted that drive assembly 36 may include a bi-state or maybe preprogrammed to index mirror subassembly 18 between desiredpositions along support 16. Alternately, drive assembly 36 may providecontinuous movement driving the mirror subassembly between an infinitenumber of positions along support 16 between its fully retracted and itsfully extended positions. In addition, drive assembly 16 may be coupledto a lock-out device or mechanism which prevents inadvertent or intendedactuation of the extension of mirror subassembly 18 while the vehicle isdriven down the highway. Such lockout device may be provided by acircuitry which detects: when the vehicle is placed in gear; or motionor speed of the vehicle. The circuitry may also be electrically coupledto and detect the operation of the ignition system. In suchcircumstances, the selection and setting of the position of the exteriormirror subassembly needs to be achieved in the non-operating mode.

Referring to FIG. 5, a second embodiment 110 of an extendable mirrorassembly is illustrated. Mirror assembly 110 includes a mounting bracket114, a support 116, which is pivotally mounted on bracket 114 by abushing 140, and a mirror subassembly 118 which is movably mounted onsupport 116. Similar to the previous embodiment, support 116 includes apair of support arms 132 and 134 which extend into housing 120 throughhousing wall 120 a. Housed in housing 120 is a drive assembly 136. Driveassembly 136 includes a motor 144 and a drive belt 146. Belt 146 ispreferably a closed loop belt and extends around a pair of pulleys 148 aand 148 b which are respectively rotatably mounted on axles 149 a and149 b in housing 120. As best seen in FIG. 5A, motor 144 includes adrive gear 150, such as a bevel drive gear, which drivingly engages acorresponding gear 151 that is drivingly coupled to pulley 148 b. Itshould be understood, however, that other drive gears, for example aworm gear or the like, may be used to drive pulley 148 b or drive belt146. Similar to the previous embodiment, motor 144 is supported by motorsupports 144 a and 144 b which are respectively adhered to or formedwith housing wall 120 a of housing 120.

Similar to the first embodiment, support arms 132 and 134 areinterconnected by a plate member 142 to which closed drive belt 146 iscoupled by a belt clamp 152. In this manner, as drive belt 146 is drivenaround pulleys 148 a and 148 b, housing 120 is translated or moved alongsupport arms 132 and 134 to its desired position.

Referring again to FIG. 5A, drive assembly 136 further includes a clutchmechanism 154. Clutch mechanism 154 is formed by axle 149 b, pulley 148b, and bevel gear 151 and a spring 156 which is mounted on axle 149 bbetween a spring stop 158 and gear 151. Spring 156 urges gear 151 intofrictional engagement with pulley 149 b in order to drivingly coupledrive assembly 136 with pulley 148 b and, in turn, support 164.Furthermore, pulley 148 b preferably includes a plurality of detents orribs 160 which engage corresponding recesses 162 formed on pulley facingside 151 a of gear 151. Therefore, as spring 156 pushes pulley 148 b andgear 151 together, detents 160 will align and engage with recesses 162to mechanically couple gear 151 and pulley 149 b together. However, whena sufficient force is applied to housing 120, in the direction ofextension detents 160 disengage from recesses 162, spring 156compresses, and gear 151 is decoupled from pulley 149 b to provide aclutch mechanism to permit manual override of drive assembly 136 and,further, provide a safety release of driver 136 from support 116.

Alternately, as seen in FIG. 5B, clutch mechanism 154′ may include afriction member 160′ which is positioned between gear 151 and pulley 148b. In this manner, when spring 156 urges gear 151 toward pulley 148 b,friction member 161 creates a sufficient force to drivingly couple gear151 to pulley 148 b. However, when a sufficient force is applied tohousing 120 in the direction of extension, spring 156 compresses and thefriction between friction member 161 and gear 151 and pulley 148 b is nolonger sufficient to drivingly couple gear 151 and pulley 148 btogether, thus decoupling drive assembly 136 from arm 116. Preferably,springs 156 of clutch assemblies 154 and 154′ are sized such that whengear 151 is stopped and pulley 149 b is moved as a result of a forceapplied to housing 120, 148 b pulley and gear 151 will disengage ordecouple from each other to permit the manual adjustment of the positionof housing 120. Likewise, if gear 151 is driven and housing 120 contactsa rigid or fixed member, springs 156 of clutch assemblies 154 and 154!are sized to permit pulley 148 b to decouple from gear 151 to therebydecouple drive assembly 136 from support 116. As will be understood bythose skilled in the art, an increase spring stiffness for spring 156will increase the amount of force required to decouple drive assembly136 from support 116.

A third embodiment 210 of an extendable rearview mirror assembly isillustrated in FIGS. 6 and 7. Mirror assembly 210 is of similarconstruction to the first embodiment and includes a mounting bracket214, a support 216, and a mirror subassembly 218, which is movablymounted on support 216. Mirror subassembly 218 includes a housing 220and a drive assembly 236 which is supported in housing 220. Support 216includes a pair of support arms 232 and 234 which extend into housing220 through sleeves 230. Similar to the previous embodiment, driver 236includes a motor 244, which is mounted in housing 220 by motor supports244 a and 244 b, and a pair of drive screws 246 and 247. Drive screws246 and 247 are rotatably mounted in housing 220 by bushing supports 246b and 247 b, respectively. In the illustrated embodiment, drive screws246 and 247 extend into and threadingly engage support arms 232 and 234to move housing 220 along support arms 232 and 234, as will be morefully described below. In the illustrative embodiment, drive screw 246includes longitudinally extending threads 248 between supports 246 bwhich are drivingly engaged by a worm gear 250 of motor 244. In thismanner, as motor 244 drives worm gear 250, drive screw 246 is rotatedabout its longitudinal axis. Drive screw's rotational movement impartsrotational movement to drive screw 247 by way of a belt 252, such as atiming belt. As noted above, drive screws 246 and 247 threadingly engagesupport arms 232 and 234 to move housing 220. In preferred form drivescrews 246 and 247 each include a compressible end portion 246 a and 247a respectively, which are threaded. End portions 246 a and 247 arespectively engage the inner surface of support arms 232 and 234, whichare internally threaded. As will be more fully described below,compressible end portions 246 a and 247 a are sufficiently flexible topermit disengagement of end portions 246 a and 247 a from the internalthreads 232 a and 234 a of support arms 232 and 234 when an obstacle isencountered or a sufficient manual force is applied to move mirrorsubassembly 220 in or out along support 216.

Referring to FIGS. 7 and 7A, shaft 254 of driver screw 246 includes aplurality of elonged slots 254 a which extend along a longitudinal axis254 b of shaft 254. In addition, shaft 254 includes an elongate bore 254c which extends into distal end 246 a of drive screw 246. Together,elongated slots 254 a and elongate bore 254 c define flexible arcuateportions 254 d on which threads 246 c are formed. In this manner, when asufficient axial force is applied to drive screw 246, arcuate members254 d compress releasing threads 246 c from engagement with threads 232a of support arm 232 to provide a manual override and to provide asafety release of drive assembly 236 from support 216. Drive screw 247includes a similar arrangement to drive screw 246. In this manner,compressible end portions 246 a and 247 a couple drive assembly 236 tosupport 216 and, further, provide a clutch mechanism for drive assembly236.

Referring to FIG. 8, a fourth embodiment 310 of an extendable exteriorrearview mirror assembly of the present invention is illustrated. Mirrorassembly 310 includes a bracket 314 of similar construction to bracket14, a support 316, and a mirror subassembly 318 which is movably mountedon support 316. Mirror subassembly 318 includes a housing 320 whichdefines a rearward facing opening 328 in which reflective assembly 324is positioned. Housing 320 is defined by a housing wall 320 a andincludes upper and lower sleeves 330 a and 330 bwhich extend intohousing cavity 320 b and provide a mounting surface for housing 320 onsupport 316, as will be more fully described below.

In the illustrated embodiment, support 316 includes a pair of spacedapart support arms 332 and 334 which are pivotally mounted to mountingbracket 314 on a pivot bushing 340. Support arm 332 extends into uppersleeve 330 a of housing 320 and includes an enlarged end, for example aflange, which defines a stop 332 a. Support arm 334 extends into lowersleeve 330 b of housing 320 and similarly includes an enlarged end 334 ato define a stop. In this manner, housing 320 is movable between an inboard position, with housing 320 in close proximity or abutting mountingbracket 314 and one or more extended positions, with an outermostextended position being defined where stops 332 a and 334 a abut sleeves330 a and 330 b.

Housed in mirror subassembly 318 is a drive assembly 326. Drive assembly326 includes a motor 344, which is supported or mounted to casing wall320 a by motor supports 344 a and 344 b, and a drive rod or tube 346.Drive rod 346 is mounted to housing 320 by one or more bushing supports352 and includes a driven gear 348 which is driven by a motor drive gear350. In the illustrated embodiment, driven gear 348 and drive gear 350are beveled gears; however, it should be understood by those skilled inthe art that other gear arrangements, for example worm gear arrangementsmay be used to rotate drive rod 346 about its longitudinal axis 346 a.Mounted to end portion 346 b of drive rod 346 is a frictional rollerassembly 356. As will be described in further detail below, frictionalroller assembly 356 frictionally engages the inner surface 334 b ofsupport arm 334 to move or translate housing 320 along support arms 332and 334.

Referring to FIG. 9, roller assembly 356 includes a mounting collar 358which is mounted on drive rod 346 and supports a plurality of rollers360. Rollers 360 are rotatably mounted to collar 358 in openings 362provided in collar 358 which permit rollers 360 to frictionally engagedrive rod 346. Collar 358 is secured to drive rod 346 by mounting platesor members 364. Collar 358 is sized such that rollers 360 alsofrictionally engage inner surface 334 b of support arm 334. In addition,rollers 360 are aligned along roller axes 363 which are skewed withrespect to longitudinal axis 346 a of drive rod 346. In this manner,when drive rod 346 is driven by motor 344 to rotate about itslongitudinal axis 346 a indicated by Arrow A in FIG. 9, rollers 360 rollabout their respective longitudinal axes 363 in a counter-direction, asindicated by Arrow B in FIG. 9. Consequently, rollers 360 impart axialmotion to drive rod 346 as drive rod 346 rotates in response to thefriction between rollers 360 and inner surface 334 b. As a result, driverod 346 moves in and out of support arm 334. As drive rod 346 moves inor out of support arm 334, housing 320 is translated or moved alongsupport arms 332 and 334. It should be understood from the foregoing, byaltering the angle of roller axis 363, the speed of the axial movementof rod 346 through support arm 334 can be adjusted. For example, with alower angle the speed is reduced as the more rotations of rod 346 areneeded to provide a given axial adjustment.

It should be understood that rollers 360 may comprise wheels or thelike. Preferably, rollers 360 comprise a relatively high frictionmaterial, for example rubber or the like. Further, drive rod 346 mayinclude a plurality of threads similar to drive rod 246, with motor 344including a worm gear similar to motor 244. Moreover, similar to mirrorassembly 210, mirror assembly 310 may include a second drive rod forextending into and frictionally engaging the inner surface 332 a ofsupport arm 332.

Referring to FIG. 10, a fifth embodiment of mirror assembly 410 isillustrated. Mirror assembly 410 includes a mounting bracket 414, asupport 416, and a mirror subassembly 418 which is slidably mounted onsupport 416. In similar manner to the previous embodiments, support 416is pivotally mounted to bracket 414 by a pivot bushing 412 and extendsinto housing 420 of mirror subassembly 418 through a sleeve 430 tothereby permit housing 420 to move between a fully retracted positionand one or more outboard positions along support 416. The outermostextended position is defined when sleeve 430 abuts stop 416 a of support416. Mounted in mirror subassembly 418 is a drive assembly 436, whichincludes a plurality of solenoid driven pistons 438, 440 and 442. Eachpiston 438, 440 and 442 has an elongated body 439, 441, and 443,respectively, which is driven by a coil 444, 446, or 448, respectively.Each tooth piston 438, 440 and 442 is laterally mounted to support 450by a support 438 a, 440 a, or 442 a, respectively. Elongated bodies 439,441, and 443 extend into piston supports 438 a, 440 a, and 442 a, whichare mounted to housing 420 by support 450 and include tapered distalends 439 a. In this manner, tooth pistons 438, 440 and 442 are guided byand free to move through supports 438 a, 440 a and 442 a. In theillustrated embodiment, support 450 comprises a transversely extendingarm which is secured to or formed with side wall 452 of housing 420.However, it should be understood that support 450 can be mounted tohousing 420 in a plurality of positions on housing wall 420 a. As bestseen in FIGS. 11A through 11C when actuated, tooth pistons 438, 440 and442 extend toward a tooth rack 454, which is mounted to or formed witharm 416. As will be more fully described below, tooth pistons 438, 440and 442 are sequentially actuated to cause housing 420 to translatealong support 416 between a fully retracted position to one or moreextended positions.

As previously noted, tooth pistons 438, 440, and 442 are eachindividually actuated and moved by solenoid coils 444, 446 and 448 suchthat their respective tapered ends 439 a extend into and engage toothrack 454. In order to translate housing member 420 toward bracket 414,tooth pistons 438, 440 and 442 are sequenced such that piston 438 isinitially extended into engagement with one of the threads on tooth rack454 as shown in FIG. 11A. As shown in FIG. 11A, the spacing “X” betweenpistons 438 and 440 is less than spacing “Y” between the correspondingthreads of tooth rack such that when second piston 440 is actuated toextend into engagement with tooth rack 454, tapered surface 440 b ofpiston 440 will engage tapered side 454 b of an adjacent thread of toothrack 454 and impart a lateral force to housing 420 such that housing 420translates in the direction indicated by arrow D, which in turn causespiston 438 to withdraw from tooth rack 454, as shown in FIG. 11B (arrowE indicates relative motion of rack 454 with respect to the pistons). Ina similar manner, following actuation of piston 440, piston 442 isactuated to extend into tooth rack 454 such that tapered side 442 bengages and translates down tapered side 454 d of another adjacentthread of tooth rack 454 causing piston 440 to disengage from tooth rack454. The sequence is repeated until housing 420 is in its desiredposition along support 416. It should be understood from the foregoing,that drive assembly 436 may include two or four or more pistons, withthe greater number of pistons providing a smoother drive function. Inaddition, pistons 438, 440 and 442 may be powered by electromagnets, orpiezoelectric elements or the like. It should be understood from theforegoing, that in order to reverse the direction of movement of housing420 along support 416, the sequencing of the piston actuation isreversed with piston 442 being first actuated, followed by piston 440,and then followed by piston 438.

Referring to FIG. 12, a sixth embodiment 510 of an extendable exteriorrearview mirror assembly is shown. Mirror assembly 510 is of similarconstruction to mirror assembly 410 and includes a mounting bracket 514,a support 516, which is pivotally mounted on bracket 514, and a mirrorsubassembly 518, which is movably mounted to support 516. Mirrorsubassembly 518 includes a housing 520 into which support 516 extends.In this embodiment, mirror subassembly 518 includes a drive assembly 526which includes a single driver piston 538. Piston 538 is driven by motor544, which induces a cycloidal motion in piston 538. Similar to theprevious embodiment, driver piston 538 sequentially engages threads ontooth rack 556 of arm 516. Piston 538 and motor 544 are mounted tohousing 520 on a support member 550 by motor supports 544 a and pistonsupports 538 a, respectively.

Referring to FIGS. 13A through 13D, piston 538 has a lozenge shaped body539 with a reduced neck 539 a on one end and a tapered thread engagingportion 539 b on its other end. Mounted to a central portion of body 539is a bushing 540 which includes an eccentrically mounted axle 542.Reduced neck 539 a extends into and is laterally supported by pistonsupports 538 a but is free to move axially through and rotate in support538 a. Axle 542 is driven by a worm gear 546 of motor 544. As axle 542is rotated, for example in a clockwise direction as viewed in FIGS. 13Athrough 13D, bushing 540 moves piston 538 from a generally verticalorientation (shown in FIG. 13A) spaced from tooth rack 556 to an angledposition in which tapered portion 539 b of piston 538 engages a taperedside 556 a of a thread of tooth rack 556 (shown in FIG. 13B). As axle542 continues to rotate in the clockwise direction, bushing 540 movespiston 538 to the left as viewed in FIG. 13C whereby tapered portion 539b is fully engaged between threads of tooth rack 556 and, further,piston 538 assumes a generally vertical position. Axle 542 continues torotate in a clockwise direction causing tapered portion 539 b to urgetooth rack 556 to the left relative to piston 538 as viewed in FIG. 13D.As a result, housing 520 moves away from mounting bracket 514 as viewedin FIG. 12. To move housing 520 to its retracted position, closer tomounting bracket 514, axle 542 is rotated in a counter-clockwisedirection, which causes tooth rack 556 to move to the right as viewed inFIGS. 13A through 13D relative to piston 538. It should be understoodfrom the foregoing, that more than one piston 538 may be used to drivehousing 520 along support 516. With an increased number of pistons, itcan be appreciated that the drive motion is smoother.

A seventh embodiment of an exterior rearview mirror assembly 610 isillustrated in FIG. 14. Mirror assembly 610 includes a mounting bracket614, a support 616, and a mirror subassembly 618 movably mounted tosupport 616. Support 616 includes a C-shaped mounting portion whichincludes a pair of spaced support arms 616 a and 616 b. Support arms 616a and 616 b are pivotally mounted to a mounting portion 614A of mountingbracket 614 on a pivot bushing 640. Cantilevered from the C-shapedmember of support 616 is a mounting arm 632 which extends into anopening 622 provided in mirror subassembly housing 620. Distal end 632 aof mounting arm 632 includes a transversely extending axle 624 whichextends into a bushing or the like (not shown) on rearward facing wall626 of housing 620. Mounted on a projecting end 624 b of axle 624 is afriction member 654 and a drive wheel or gear 652. Drive wheel 652 isrotatably mounted on free end 624 b but is urged into frictionalengagement with friction member by a spring 655, which is mountedbetween drive wheel 652 and an enlarged end portion 665 of axle 624.Spring 655 urges drive wheel 654 into frictional engagement withfriction member 654 in order to drivingly couple motor 644 to arm 632.In this manner, when motor 644 is coupled to mounting arm 632 andactuated, housing 620 is rotated about axle 624. However, when housing620 moves into engagement with a rigid structure or object or when asufficient rotational force is applied to housing 622 about axle axis624 a to compress spring 655, motor 644 is drivingly decoupled frommounting arm 632 to permit manual adjustment of the position of housing620 about axle 624. It should be understood, that friction member 654may include a plurality of detents or the like for engaging acorresponding plurality of recesses or the like formed in drive wheel652 in a similar manner to the previous embodiment shown in FIG. 5A.

In the illustrative embodiment, axle 624 is shown as an integral part ofmounting arm 632; however, it should be understood that a separate axlemay be mounted to free end of 632 a. Furthermore, friction member 654may be omitted with drive wheel or gear 652 frictionally engagingmounting arm 632 or may include detents to engage corresponding recessesformed in friction member 654 or mounting arm 632. These and othervariations may be appreciated from the preceding description.

Referring to FIG. 15, an eighth embodiment 710 of an extendable rearviewmirror assembly of the present invention is illustrated. Similar to theprevious embodiments, mirror assembly 710 includes a mounting bracket714, a support 716, and a mirror subassembly 718 movably mounted tosupport 716 by such that mirror subassembly 718 can be moved between afully retracted position (shown in solid lines in FIG. 15) and anextended position, with one such extended position illustrated inphantom lines in FIG. 15. Preferably, support 716 is pivotally mountedto mounting bracket 714 on a pivot bushing 740. Mirror subassembly 718is pivotally mounted to support 716 by a link 722. Link 722 extends intosupport 716 and is rotatably mounted on one end 722 a to support 716 bypivot pin or axle 724 or the like. Support 716 includes an opening 716 awhich is sized to accommodate the angular motion of link 722 between themirror's fully retracted position and the mirror's fully extendedposition. Free end 722 b of link 722 is similarly rotatably mounted tohousing 720 on a pivot pin or axle 726. In the illustrated embodiment,pivot pin 726 extends through an upper wall 728 of housing 720 and intothe interior 730 of housing 720 and is rotatably supported in upper wall728 and bottom wall 732 of housing 720. It should be understood that pin726 may be supported in the interior 730 by an intermediate structure.

As best seen in FIG. 15, mirror subassembly 718 is moved between itsretracted position and extended positions by a drive assembly 736. Driveassembly 736 includes a motor 744 which is mounted to housing wall 720 aof housing 220 by motor supports 744 a. Motor 744 includes a drive gear746, for example a worm gear, which drives a drive gear 750 mounted onaxle 724. Mounted below link 722 on axle 726 is a driven wheel orsprocket 752 which is frictionally engaged by drive gear 750. Axle 724similarly includes a driven sprocket or wheel 754 which is driven bydriven wheel 752, as will be more fully described below. Extendingaround driven sprocket 752 and sprocket 754 is a closed loop belt 758,such as a timing belt. In order to drivingly couple drive gear 750 todriven gear 752, axle 726 includes a spring 760 which is positionedbetween drive gear 750 and a retaining ring 762 or the like which ismounted to axle 726. In this manner, when motor 744 is powered, wormgear 746 drives drive gear 750, which in turn is urged into frictionalengagement with driven gear 752 by spring 760, which results inrotational movement of shaft 726 about its longitudinal axis 726 a. Link722 is rotatably supported on axle 724 such that when axle 726 rotatesabout its longitudinal axis 726 a link 722 moves housing 720 from itsretracted position to its fully extended position shown in phantom inFIG. 15.

In addition, in order to reduce the aerodynamic drag of mirrorsubassembly 716, upper wall 728 of housing 720 includes a recessedportion 728 a which permits link 722 to be mounted flush with an uppersurface 720 b of housing 720 and yet permits the full range of motion oflever 722 between the mirror's fully retracted position to its fullyextended position.

Referring to FIG. 16, a ninth embodiment of the extendable rearviewmirror assembly 810 of the present invention is illustrated. Mirrorassembly 810 includes a mounting bracket 814, a support 816, and amirror subassembly 818 which is pivotally mounted to and supported bysupport 816. Similar to the previous embodiment, support 816 ispivotally mounted to mounting bracket 814 on a pivot bushing 840 andincludes a pair of links 822 and 823 for selectively pivotally mountingmirror subassembly 818 to support 816. Mirror assembly 818 is of similarconstruction to mirror assembly 710, with the addition of a second linkmember 823 which provides additional vertical support for mirrorsubassembly 818 on support 816. Link member 822 includes a similar drivemechanism to link 722 and selectively moves mirror subassembly 816between a fully retracted position and one or more extended positions asshown in FIG. 16. It should be understood that second link member 823may also include a similar drive mechanism to 822.

Furthermore, while one form of the invention has been shown anddescribed, other forms will now be apparent to those skilled in the art.For example, the various embodiments illustrate electrically actuateddrive assemblies, but it should be appreciated that other actuationsystems may be used, such as a pneumatic system. In addition, as notedin reference to the first embodiment, the support may be fixed to themounting bracket or have a breakaway mounting or a folding mounting or,further, may be directly mounted to the vehicle. The embodiment of theinvention shown in the drawings is not intended to limit the scope ofthe invention which is defined by the claims which follow.

The embodiments of the invention in which we claim exclusive property orprivilege is claimed are defined as:
 1. An electrically extendableexterior rearview mirror assembly comprising: a mirror subassemblyhaving a housing including a reflective element; a bracket adapted formounting to a vehicle; a support pivotally mounting said mirrorsubassembly to said bracket, said support comprising a pair of supportarms, said at-least-one support arms extending into said housing, saidmirror subassembly being movable along said support arms in a directionof extension or retraction and having a fully retracted viewing positionand at least one outboard viewing position for said mirror subassembly,and said support arms having outboard ends and being interconnected atsaid outboard ends; and a drive assembly drivingly coupled to saidsupport at said outboard ends of said support arms, said drive assemblyselectively moving said mirror subassembly along said support arms, andsaid drive assembly disengaging from said support when a force isapplied to said housing in said direction of extension or refractionwhereby said mirror subassembly can be manually moved along said supportin said direction of extension or retraction.
 2. The electricallyextendable exterior rearview mirror assembly according to claim 1,wherein said support arms are interconnected at their outboard ends by aan interconnecting member, said member being coupled to said driveassembly.
 3. The electrically extendable exterior rearview minorassembly according to claim 2, wherein said member is releasably coupledto said drive assembly wherein said member decouples from said driveassembly when said force is applied.
 4. The electrically extendableexterior rearview mirror assembly according to claim 2, wherein saiddrive assembly includes a motor and a belt, said belt being coupled tosaid member, said motor driving said belt to move said housing alongsaid support.
 5. The electrically extendable exterior mirror assemblyaccording to claim 4, wherein said drive assembly further includes adrive pulley and an idler pulley, said belt extending around said drivepulley and said idler pulley, and said motor driving said drive pulley.6. The electrically extendable exterior rearview mirror assemblyaccording to claim 2, further comprising a clutch, said clutch drivinglydecoupling said drive assembly from said member when said force ofsufficient magnitude is applied to said mirror subassembly in saiddirection of extension such that said mirror subassembly can be manuallymoved along said support.
 7. The electrically extendable exteriorrearview mirror assembly according to claim 2, said drive assemblyincludes at least one drive member, said drive member being drivinglycoupled to said interconnecting member at to thereby move said mirrorsubassembly along said support arms.
 8. The electrically extendableexterior rearview mirror assembly according to claim 7, wherein saiddrive member engages said interconnecting member to thereby move saidminor subassembly along said support arms.
 9. The electricallyextendable exterior rearview minor assembly according to claim 8,wherein said drive member comprises a lead screw.
 10. The electricallyextendable exterior rearview minor assembly according to claim 8,wherein said drive member comprises a belt.
 11. The electricallyextendable exterior rearview mirror assembly according to claim 10,wherein said belt comprises a timing belt.
 12. The electricallyextendable exterior rearview mirror assembly according to claim 8,further comprising a clutch, said clutch drivingly decoupling said driveassembly from said support when a force of sufficient magnitude isapplied to said mirror subassembly into said direction of extension suchthat said mirror subassembly can be manually moved along said support.13. The electrically extendable exterior rearview minor assemblyaccording to claim 12, wherein said interconnecting member includes saidclutch.
 14. The electrically extendable exterior rearview mirrorassembly according to claim 12, wherein said drive assembly includes amotor, a motor drive gear, and a driven gear, said driven gear drivingsaid drive member.
 15. The electrically extendable exterior rearviewmirror assembly according to claim 14, wherein said driven gear includessaid clutch.
 16. The electrically extendable exterior rearview mirrorassembly according to claim 7, wherein said housing of said mirrorsubassembly includes a pair of sleeves, said support arms extending intosaid sleeves.
 17. The electrically extendable exterior rearview mirrorassembly according to claim 16, wherein said housing is slidably mountedon said support arms by said sleeves.
 18. The electrically extendableexterior rearview mirror assembly according to claim 2, wherein each ofsaid support arms includes a distal end portion and a proximal endportion, said proximal end portions pivotally mounting said mirrorsubassembly to said bracket.
 19. The electrically extendable exteriorrearview mirror assembly according to claim 1, wherein said driveassembly includes a lead screw, said support arms being interconnectedby a member at their respective outboard ends, and said lead screwextending through said member and drivingly engaging said member tothereby move said mirror assembly along said support arms.
 20. Theelectrically extendable exterior rearview mirror assembly according toclaim 19, Wherein said member includes flexible thread engaging portionswhereby said flexible thread engaging portions disengage from said leadscrew when a force is applied to said housing in said direction ofextension thus permitting manual adjustment of said housing along saidsupport.
 21. The electrically extendable exterior rearview mirrorassembly according to claim 1, further comprising a break-away mounting,said break-away mounting providing limited pivotal movement of saidsupport about said bracket.
 22. The electrically extendable exteriorrearview minor assembly according to claim 1, wherein said support armsare visible exteriorly of said rearview mirror assembly when said mirrorsubassembly is in said outboard position.
 23. An electrically extendedexterior rearview mirror assembly comprising: a mirror subassemblyhaving a housing and a reflective element; a bracket adapted formounting to a vehicle; a pair of support arms pivotally mounting saidminor subassembly to said bracket, said support arms extending into saidhousing, and said mirror subassembly being movable along said supportarms and having a fully retracted viewing position and at least oneoutboard viewing position for said mirror subassembly, and said supportarms being substantially within said housing when said subassembly isfully retracted and said support arms being visible exteriorly of saidrearview mirror assembly when said mirror subassembly is moved to saidoutboard position; and a drive assembly drivingly coupled to outboardends of said support arms, said drive assembly selectively moving saidmirror subassembly along said support arms.
 24. The electricallyextendable exterior rearview mirror assembly according to claim 23,wherein said support arms arc interconnected by a member, said driveassembly drivingly coupling to said member to selectively move saidminor subassembly along said support arms.
 25. The electricallyextendable exterior rearview minor assembly according to claim 24,further comprising a clutch, said clutch drivingly decoupling said driveassembly from said support arms when a force of sufficient magnitude isapplied to said mirror subassembly into a direction of extension of saidmirror assembly such that said mirror subassembly can be manually movedalong said support.
 26. The electrically extendable exterior rearviewminor assembly according to claim 25, wherein said interconnectingmember includes said clutch.
 27. The electrically extendable exteriorrearview mirror assembly according to claim 26, wherein said driveassembly includes a lead screw and a motor, said motor driving said leadscrew to drivingly engage said interconnecting member through saidclutch.
 28. The electrically extendable exterior rearview mirrorassembly according to claim 27, wherein said lead screw is supported bysaid housing.
 29. An electrically extendable exterior rearview mirrorassembly comprising: a mirror subassembly having a housing and areflective element supported in said housing; a bracket adapted formounting to a vehicle; a pair of support arms pivotally mounting saidmirror subassembly to said bracket, said support arms extending intosaid housing, and said mirror subassembly being one outboard viewingposition for said mirror subassembly, and said support arms beingsubstantially within said housing when said subassembly is fullyretracted and said support arms being visible exteriorly of saidrearview mirror assembly when said mirror subassembly is moved to studoutboard position: a drive assembly drivingly coupled to said supportarms, said drive assembly selectively moving said mirror subassemblyalong said support arms, said support arms being connected by aninterconnecting member, said drive assembly driving coupling to saidinterconnecting member to selectively move said mirror subassembly alongsaid support arms, said drive assembly including a lead screw and amotor, said lead screw being supported by opposed end walls of saidhousing; and said interconnecting member including a clutch, and saidmotor driving said lead screw to drivingly engage said interconnectingmember through said clutch, and said clutch drivingly decoupling saiddrive assembly from said support arms when a force of sufficientmagnitude is applied to mirror subassembly into a direction of extensionof said mirror assembly such that said mirror subassembly can bemanually moved along said support.
 30. The electrically extendableexterior rearview mirror assembly according to claim 29, wherein saidsupport arms are interconnected by said interconnecting member at theirrespective outboard ends.
 31. The electrically extendable exteriorrearview minor assembly according to claim 29, wherein saidinterconnecting member includes flexible threaded engaging portionswhereby said flexible thread engaging portions disengage from said leadscrew when a force is applied to said housing in a direction ofextension or retraction thus permitting manual adjustment of saidhousing along said support arms, said flexible thread engaging portionsdefining said clutch.
 32. The electrically extendable exterior rearviewminor assembly according to claim 29, wherein said housing of saidmirror assembly includes a pair of sleeves, said support arms extendinginto said sleeves.
 33. The electrically extendable exterior rearviewmirror assembly according to claim 29, further comprising a break-awaymounting, said break-away mounting providing limited pivotal movement ofsaid support about said bracket.